How does air infiltration impact HVAC systems?

Air infiltration significantly impacts HVAC systems by leading to increased energy usage. When outside air leaks into a building through gaps and cracks in the building envelope, it forces the HVAC system to work harder to maintain the desired indoor temperature. This additional workload results in greater energy consumption, as the system must both heat or cool air that is entering from outside and maintain the comfort levels within the space.

This aspect is crucial because proper air sealing and insulation are foundational to an energy-efficient building. By minimizing air infiltration, the HVAC system can operate more efficiently, reducing energy costs and improving overall comfort.

The other options do not accurately represent the impacts of air infiltration. For instance, air infiltration would not stabilize indoor air quality, nor does it optimize humidity levels; instead, it can lead to fluctuations in both areas. While gaps in the building envelope may allow for some fresh air circulation, they more commonly allow unwanted pollutants and humidity levels to fluctuate, making it harder to maintain consistent air quality and moisture control. Thus, the role of air infiltration is detrimental in the context of HVAC efficiency and performance.